Many medical procedures have been improved over the past decades by the use of arthroscopic devices. Treatments that once required invasive procedures and extended hospital stays are routinely done on an outpatient basis with an abbreviated recovery period. Endoscopes alone and in combination with imaging systems are used for arthroscopy as well as other diagnostic procedures. The endoscopes and optical couplers sometimes used to connect the endoscope to an imaging system must be sterilized before they can be used in an evasive procedure.
The most common, quickest, and cost effective way to sterilize a piece of equipment is to use an autoclave. This subjects the tool to a high pressure, high temperature and high moisture environment proven to effectively kill pathogens.
The surfaces of the optical elements used in these tools should have no debris or substance on them that will obscure or degrade the quality of the image they are transmitting. The optical elements are positioned within a metal tube or sheath and isolated from the environment by sealing the ends of the sheath. Typically, an optical element with metalized edges is used to seal the ends of the sheath or tube. The metalized edges of the optical element are brazed or soldered into the sheath or tube to form the hermetic seals.
As can be imagined subjecting these optical tools to the environment inside of an autoclave can be detrimental to its longevity if moisture were to breach the hermetic seals. If sufficient moisture penetrates the seals to allow condensation on the internal surfaces of the optical element it will distort the view provided by the optics. If the optical elements contained within the sheath can be chemically attacked by moisture that has condensed on their surfaces the distortion to the view will be permanent and remain if the condensation dissipates.
Various methods of securing an optical element in an autoclavable optical tool are known. These include braising, fritting, O-rings, adhesive and brazing. However, each of these methods have their disadvantages. These disadvantages range from cost and labor required to short life cycles.
What is needed is a method for mounting an optical element or window into an optical train that is quick, inexpensive, easy to assemble and provides a reasonable life cycle.